Fuel injection control



A I V iii W. F. ISLEY Filed July 27, 1953 FUEL INJECTION CONTROL June12, 1956 70 f/VG/A/f N M R n I. a A. 6 i f 2. 1% Ni V Q a 32 3 a m/ Z 22 1 0D B A 22 3 INVENTOR. WALTER F. IS LEY ATTO RNEYS United StatesPatent FUEL INJECTION CONTROL Walter F. lsley, Grosse Pointe, Mich,assignor to Continental Motors Corporation, Detroit and lvlnsliegon,Mich, a corporation of Virginia Application July 27, 1953, Serial No.370,593

3 Claims. (Cl. 123-440) The present invention relates to fuel injectioncontrol means for the purpose of controlling the operation of fuelinjection pumps and specifically to the actuation of such means inrelation to manifold pressures of supercharged engines.

In the regulation of fuel delivery from variable discharge pumps inaccordance with manifold pressures, the results heretofore obtained donot provide the fuel economy desired nor the most efficient fuel-airratios obtainable at higher engine speeds. If some compensation is notmade for the higher speeds, the fuel-air ratios become excessively rich.The droop in air rate at higher speeds is due to the volumetricefficiency change of the engine with speed, whereas the injector is apump with essentially constant volumetric efficiency, hence the fuelrate is greater than that desired. Valves heretofore utilized to solvethis problem have not proven satisfactory since they are unreliable,sensitive to barometric pressure, and ineffective on part throttlemetering.

Therefore an object of this invention is to prevent the fuel-air ratiofrom becoming excessively rich due to the droop in air rate at highspeeds, by providing a device which will effect a corresponding highspeed droop in fuel metering rate.

Another object of this invention is to eliminate barometric sensitivityand make fuel metering more dependent on engine speed by providing ametering control valve which will effectively sense the pressuredifferential across the engine supercharger, since supercharger pressurerise is a function of engine speed.

Still another object of the invention is to simplify the fuel meteringcontrol by providing a valve comprising a minimum of connections andadjusting means, and utilizing none or" the mechanical connections tothe throttle which heretofore have proven unreliable, since throttleposition is not a true indication of engine speed.

With these and other objects as will be readily understood by thoseskilled in the art, reference is made to the following description anddrawing wherein like characters refer to like parts throughout theseveral views, and in which Fig. 1 is diagrammatic illustration showingthe arrangement and operation of the invention, and

Fig. 2 is a central vertical sectional view of the actual constructionof the valve shown in the lower portion of Fig. 1. i

In the drawing, referring first to Fig. 1, a supercharge engine (notshown) is indicated with the supercharger 10, its air inlet 11 and itsoutlet 12 leading to the engine manifold. A suitable variable outputfuel pump is indicated at 13, the variation of output being controlledby the position of a pin 13A determined by the bellows 13B, theexpansion and contraction of which is due to the variation of pressurein the enclosing pressure compartment 13C. A decrease of pressure oncompartment 13C results in a reduced fuel rate output of the pump 13.

From the diagram of Fig. 1, it will be noted that three conduits 14, 15and 16 are open to the main air conduit, conduit 14 opening to the airintake close to but ahead or upstream of the throttle 17. The secondconduit 15 is open to the air intake behind the throttle 17 ordownstream thereof but ahead or upstream of the supercharger 10. Thethird conduit 16 is open to the air outlet downstream or beyond theoutlet of the supercharger.

As indicated, the conduit 14 leads first to a check valve 14A, beyondwhich it branches, one branch 14B terminating in the jet 14C of aventuri 18. The other branch 14D leads through a regulating valve 19 toa conduit 20 connected to the low pressure chamber of the venturi 18.

The conduit 15 is also branched with one branch 15A leading to theoutlet of a needle valve 21 enclosed in a casing 22 of a valve structureand fixed to a diaphragm 23 in the casing while the other branch 1513leads to the chamber 31 of the valve structure under the diaphragm, i.e., to the side of the latter opposite the needle valve 21.

The conduit 16, which is constructed in open communication with airoutlet 12, is arranged to receive the flow of air from the jet 14C andis also connected to the low pressure chamber of the venturi 18, towhich is also connected the conduit This conduit 2% as stated above, isopen to the conduit MD, and is connected to both the pressurecompartment 13C of the pump and through a passage 228 to chamber 22 ofthe valve structure, terminating in the latter on the needle valve sideof the diaphragm 23. A suitable restriction 23A is placed in conduit25;" between conduit 14D and the connection to the pump.

The control means indicated in Fig. 1, consists of two parts, namely theidling control part A and the high speed control part B, control part Aserving to control the pump at idle or with the throttle open only asmall amount. As the throttle is opened, however, this part A of thecontrol means becomes inactive because check valve MA closes, and theother control part, designated B, takes over control. The control partB, just referred to, consists of the conduits 15 and 16 and the valvestructure shown in the lower portion of Fig. l, the actual structure ofthe valve being shown in Fig. 2. The construction and operation ofcontrol part A is described and claimed in my copending application Ser.No. 370,535, filed July 27, 1953, and entitled Fuel Injection Control.

T he valve structure consists of the housing 22, which for convenienceis preferably a rather thick walled casing closed at its bottom end by acap member 30 between which and the end of the chamber walls of housing22 is clamped the diaphragm 23.

The cap 30 is provided with a well or chamber Si in which the spring 23Ais located and held between the diaphragm 23 and the head of anadjusting screw 32 threaded through the bottom wall of the cap, theprojecting end of screw 32 being protected by a cap or cover 33.

In the chamber 22A formed within the casing 22, above and fixed to thediaphragm 23, is the valve 21, slidably mounted in a sleeve 34 threadedinto the upper wall of the chamber. The pointed upper end of the valveopens and closes communication between passage 15A within the upper wallof the casing 22 and chamber 22A through passages 22B and 35. Thepassage 15B is shown as extending partially through the upper wall, thendown within the side wall where it connects, through a suitable nipplewith a passage 1115 opening to the chamber 31 in cap 3% by means of thepassage 115A.

Also in the upper wall of casing 22 is a through passage 228, to one endof which is connected conduit 20 and to the other end of which isconnected the vacuum As shown in the drawing, the bearing sleeve 34 forthe valve 21 is provided with suitable openings 36 so as not to blockthe through passage 22B. And the spring 23B is shown as mounted betweenthe lower end of sleeve 34 and a suitable shoulder on the valve 21.

As noted above and described in my copending application aforesaid,there is a drop in pressure from conduit 16 to 20 during closed throttleor idling operation, because check valve 14A is open and this drop inpressure is caused by the venturi construction 140. On opening thethrottle, the proper fuel and ratio is maintained during the firstportion of the throttle opening; that is, during engine idling operationby means of the operation of control part A. Almost immediately thecheck valve 14A is closed as the throttle is opened to increase enginespeed, and during this intermediate engine speed operation, beforecontrol part B takes over, the pressures in conduit 16 and 20 aresubstantially the same and pressure compartment 13C of the injectionpump is directly responsive to pressure variations in conduit 16 and 20,and during this intermediate engine speed operation the correct fuel andair ratio is automatically maintained. As the throttle moves to fullopen position, the fuel and air mixture tends to become too rich, andthus control part B is constructed and arranged to take over anddecrease the fuel rate of the injection pump delivery.

As the throttle opens and the supercharger speeds up, the pressuredifferential between the intake and delivery of the supercharger greatlyincreases while the pressure in conduit also increases from asub-atmospheric to substantially atmospheric pressure. The pressure inconduit 16 will remain subatmospheric until the throttle nears fullopening but will become greater and greater until it becomesover-atmospheric. In response to such increasing pressures in conduit16, the pressure in pump pressure compartment 13C, will also beincreasing. Chamber 22A is open to conduit 16-20 and chamber 31 is opento conduit 15 and 158. However, as the pressure increases in chamber 22Aabove the diaphragm as a result of the increase in pressure in conduits1620, it tends to open valve 21, and when such pressure exceeds thecombined effort of the spring 23A and the pressure in the chamber 31below the diaphragm, valve 21 will open, permitting pressure flow fromchamber 13C through the open valve passage 22B to passage 15A and thencethrough conduit 15 to the supercharger inlet 11. Because of a pressuredrop from conduit across orifice 20A, the flow through the valve reducesthe pressure to chamber 13C, hence variably reducing the rate of fueloutput of the injector pump 13 in the higher ranges of engine speed. Thedegree or magnitude of the pressure limiting effect in compartment 130is a function or result of the relative rate of spring 23A, the size orrate of opening caused by the corresponding movement of valve 21, andthe size of the restricted orifice 20A.

I claim:

1. In an apparatus for supplying fuel to an internal combustion enginehaving an air intake system, a supercharger in said system, and avariable delivery engine driven fuel injection pump provided with apressure compartment and with a pressure responsive control device insaid compartment and operable to vary the fuel output of said injectionpump, a control means for controlling the pressure in the pressurecompartment of said pump, a conduit connected with said air intakeupstream of said supercharger and another conduit connected with saidair intake downstream of said supercharger, and with the pressurecompartment of said pump ported means and a valve structure disposedbetween said conduits and comprising a valve casing, provided with acompartment and a flexible diaphragm dividing said valve compartmentinto upper and lower chambers, a valve carried by said diaphragm andactuated to control the ported means connecting said first conduit withsaid second conduit, said second mentioned conduit open to said upperchamber, said first mentioned conduit open to said lower chamber,adjustable spring means in the lower chamber urging the valve to closedposition, a precalibrated restricted orifice in said secondconduitintermediate the connection of the second conduit with the airintake system of the engine and the connection between said secondconduit and the pressure compartment of said pump, said valve opening inresponse to pressure rise in said second conduit to reduce the pressurein said pressure compartment of the pump by reason of the drop inpressure produced across said precalibrated restricted orificeaforesaid.

2. In an apparatus for supplying fuel to an internal combustion enginehaving an air intake system, a supercharger in said system, and avariable delivery engine driven fuel injection pump provided with apressure compartment and with a pressure responsive control device insaid compartment and operable to vary the fuel output of said injectionpump, a control means for controlling the pressure in the pressurecompartment of said pump, a conduit connected with said air intakeupstream of said supercharger and another conduit connected with saidair intake downstream of said supercharger and with the pressurecompartment of said pump, a precalibrated restricted orifice in saidsecond mentioned conduit, a port connecting said conduits, a valvecontrolling said port, means urging said valve to closed position, andvalve actuating means operable in response to increasing pressures insaid second conduit on opening said throttle to full open position toopen said port, whereby to induce flow from said second conduit to saidfirst conduit and causing a pressure drop across said precalibratedrestricted orifice and thereby causing a decrease in pressure in saidpressure compartment of said pump.

3. In an apparatus for supplying fuel to an internal combustion enginehaving an air intake system, a supercharger in said system, and avariable delivery engine driven fuel injection pump provided with apressure compartment and with a pressure responsive control device insaid compartment and operable to vary the fuel output of said injectionpump, a control means for controlling the pressure in the pressurecompartment of said pump, a conduit connected with said air intakeupstream of said supercharger and another conduit connected with saidair intake downstream of said supercharger and with the pressurecompartment of said pump, a precalibrated restricted orifice in saidsecond mentioned conduit, a port connecting said conduits, a valvecontrolling said port, means urging said valve to closed position, andvalve actuating means operable in response to increasing pressures insaid second conduit on opening said throttle to full open position toopen said port, whereby to induce flow from said second conduit to saidfirst conduit and causing a pressure drop across said precalibratedrestricted orifice and thereby causing a decrease in pressure in saidpressure compartment of said pump, said means urging said valve toclosed position comprising adjustable spring means and connections tothe pressure in said first conduit.

References Cited in the file of this patent UNITED STATES PATENTS

